1. Field of the Invention
The present invention relates to a phase shifting circuit, and more particularly to a phase shifting circuit capable of shifting the phase of each rectangle wave input signal by a predetermined degree to output the phase-shifted signal.
2. Description of Related Art
Phase shifting circuits have been used in various fields, for example, for demodulating signals in communications, for generating multiphase clocks in computers, etc., so as to input cyclical clock signals and output clock signals having phases shifted by a predetermined amount respectively.
FIG. 5 is a block diagram of a conventional phase shifting circuit disclosed in the patent document 1. In the circuit, constant current circuits 18a and 18b are used to charge capacitors 16a and 16b and comparators 14a and 14b are used to delay input signals A and A′ until the charged potentials exceed the potentials of reference power supplies 20a and 20b respectively, thereby the phases of the input signals are shifted by a predetermined time and output, respectively.
The patent document 2 discloses a phase shifting circuit, in which a pair of differential gates input complementary signals, a resistor, and a capacitor are connected between the drains of the pair of gates to output a pair of complementary triangle wave signals, which are then shaped by a comparator to output each input clock signal delayed by 90°.    [Patent document 1] Japanese Patent Application Laid Open No. 2001-345677    [Patent document 2] Japanese Patent Application Laid Open (Translation of PCT Application) No. 11(1999)-505987